Hydraulic pumps or motors



Man-ch30, 1965 R. J. IFIELD HYDRAULIC PUMPS OR MOTORS 2 Sheets-Sheet. 1

Filed May 25, 1963 March 30, 1965 R. J. IFIELD 3,175,511

' HYDRAULIC PUMPS on MOTORS Filed May 23, 1963 2 Sheets-Sheet 2 United States Patent land Filed May 23, 1963, Ser. No. 282,697 4 Claims. (Cl. 193-462) This invention relates to hydraulic pumps or motors of the kind comprising a multi-part body, a driving shaft rotably mounted in the body, a port block mounted in the body with a curved surface held in sliding contact with a complementarily curved surface of the body so as to allow adjustment of the angle between the driving shaft and a flat surface presented to one end of the driving shaft by the side of the port block opposite the curved surface, a fluid operable piston for applying a variable force to the port block in order to vary said angle, a cyinder block rotatably mounted on the port block and having an end surface in contact with the flat surface of the port block, a universal or equivalent coupling interconnecting the driving shaft and cylinder block, a plurality of pistons accommodated respectively in .an equal number of angularly spaced cylinders extending longitudinally through the cylinder block, a plurality of piston rods connected to the pistons respectively and connected by ball-and socket or equivalent joints to angularly spaced portions of a driving head which is mounted on and rotatable with the driving shaft so that as the driving shaft rotates the pistons reciprocate, the ends of the cylinders remote from the driving head being arranged to register in turn with an inlet port and an outlet port in the port block as the cylinder block rotates, said inlet port and outlet port being in communication respectively with an inlet and an outlet in the body.

It is desirable in pumps or motors of this kind for the ports to extend through the port block from the flat surface to the curved surface in a direction which is generally parallel to the axis of rotation of the cylinder block. In this case the inlet and outlet in the body must register with the ends of the ports in the curved surface of the port block irrespective of the angular setting of the latter. To admit of this the inlet and outlet and/ or the ports in the port block must be elongated in a circumferential direction. Because of their elongated shape however, the pressure of the liquid in the high pressure port (the inlet port in a motor or the outlet port in a pump) acts between the curved surfaces and tends to tilt the port block out of contact with the body. The object of the invention is to minimise this tendency.

According to the inveniton, in a pump or motor of the kind specified, the inlet port and outlet port in the port block extend from the fiat surface to the curved surface thereof in a direction which is generally parallel to the axis of rotation of the cylinder block, and a further fluid operable piston subjected to the pressure at the inlet or outlet, whichever is the greater, is caused to act on the port block in a direction to counteract forces tending to tilt the port block out of contact with the curved surface of the body.

In the accompanying drawings.

FIGURE 1 is a sectional side elevation of one example of a pump embodying the invention.

FIGURE 2 is a section on the line 22 of FIGURE 1.

FIGURE 3 is a section of part of the pump shown in FIGURE 1 and FIGURE 4 is a diagram showing the fluid connection to various parts of the pump.

Referring to the drawings there is provided a multipart hollow body 1 and a driving shaft 2 rotatably mounted in anti-friction hearings in one end of the body. One end 3,175,51 l Patented Mar. 30, 1965 ice of the driving shaft is intended to be connected to the output shaft (not shown) of an engine and the other end extends into the hollow part of the body. A driving head 3 is engaged with this end of the driving shaft and is mounted in a surrounding anti-friction bearing 4 interposed between its outer periphery and the inner wall of the body. In the other end of the body is a port block 5 which, on one side, has a flat rectangular surface 6 presented towards the inner end of the driving shaft. On the opposite side of the port block is a part-cylindrical surface 7 which is slidably engaged in a complementarily shaped groove 8 in the adjacent end of the body. The part cylindrical surface of the port block is held in contact with the surface of the groove by springs 9. Moreover the groove 8 is of greater length in a circumferential direction than the curved surface of the port block 5 so that the latter can be slid along the groove to allow the angle between the flat surface 6 and the driving shaft 2 to be varied.

A hollow spigot 10 extends from the fiat face of the port block towards the end of the driving shaft and provides a mounting for a cylinder block 11. The cylinder block is of cylindrical shape and has a central hole accommodating an anti-friction bearing 12 mounted on the spigot. Moreover, the cylinder block has a flat end surface which is in contact with the flat surface of the port block and is connected to the driving shaft 2 by means of a universal coupling 13.

In the hollow in the spigot 10 is a cuplike part 14 which is telescopically engaged with a second cup-like part 14a which is accommodated in an aligned recess in the port block. Moreover, mounted between the parts 14 and 14a are compression springs 9 which serve to hold the port block in contact with the curved surface of the groove.

The cylinder block 11 has a plurality of equiangularly spaced cylinders 15 extending through it parallel to its axis of rotation. The cylinders are of stepped form with their narrower ends constituting ports 16 in the flat surface of the cylinder block. The cylinders contain respectively pistons 17, to which are connected piston rods having ball ends 18 engaged in hemispherical sockets formed at angularly spaced positions around the driving head 3 and are held there by a retaining plate 19 which is bolted on the adjacent face of the driving head.

The flat surface of the port block has a pair of arcuate ports 20, 21 formed therein and these are in communication, as will be described, with an inlet 22 and an outlet 23 in the body respectively. Each in turn of the ports 16 in the cylinder block communicate with the arcuate ports as the block rotates.

The arcuate ports 20, 21 are in communication, through passages 24, with a pair of elongated ports 25, 26 respectively formed in the curved surface 7 of the port block. These ports register with a pair of further ports in the body which are in communication with the inlet and outlet respectively.

In a pair of adjacent corners of the fiat surface 6 of the port block are a pair of cylinders 27, 27a respectively which extend parallel to the axis of rotation of the cylinder block and terminate within the port block, one cylinder being on the same side of the flat face as the arcuate port 20 and the other on the same side as the arcuate port 21. Each cylinder contains a hollow piston 28 which accommodates a compression spring 29 interposed between the piston and the closed end of the cylinder to load a stem of the piston into contact with a part 30 mounted on the body. The cylinder 27 on the side of the flat face incorporating the arcuate inlet port 20 is connected to the outlet of the pump through control means 31 whereby liquid can be made to enter the space between the piston and the closed end of the cylinder at a variable pressure. The

other cylinder 27a is connected directly to the outlet of the pump so that liquid will enter the space between the piston and the closed endof this cylinder atoutlet pressure, a a

' Whenthei'pump is in "operation, theport blocks is set with its flat face 'atan "angle to the driving shaft '2, and

thedriving shaft'is driven by the engine. and in turn drives the port block through the driving head '3 and universal V coupling-13. Because of the angle between the flat face a of 'theport block and'the driving shaft, the pistons are "reciprocated by the rotation'of the cylinder'block. The

The pistons 28 'are'urged againstthe part 30 bythe hsprings 29 and by the fluid pressure in theircylinders 27, "27a which will vary with speed. When in operation, the 'fiat'surface of theport block is inclined tothe axis of the driving shaft at agiven angle the combined forces of the "pistons acting on the body'balance the inherent tendency for the port block to move in a direction to increase the inclination of theflat surface, this tendency also increasing with speed. Therefore, byvaryingthe proportion of the pump output pressure which is admitted tofthe cylinder 27, bythe control means,'the obliquity'ofthe port block can be' varied and'hence'the output pressure of the pump'may be controlled. "Moreover; the other piston in the port block which is subjected to the pump output pres- "sure 'at all times 'actswith a force which serves to balance the forces tending to tilt the port block and in particular those 'due'to the 'fluid pressures acting'betweenthe outlet and'the registeringportsi2'5, 26] in the port block.

Incertain circumstances the pump maybe called upon to act asa motor and for this purpose one-way valves 32 'are' provided as shown in FIGURE 4 to' reverse the connectionsto' the cylinders 27, -27a andi to'thecontrol means Having thus described myfinvention' whatl claim as 'newand desire to secure byLetters Patent is:

1. A hydraulic device of. the type described, comprising a multi-part bodyihavingan'interior surface of concave arcuate shape, a drivingjs'h'aft'rotatably mounted in said 'bodyextending intosaid body opposite said concave arcuate surface,.a driving head fixed to said driving shaft'with- *in'said "body 'oppo site'a portion of said concave arcuate surface, a port block including an inlet'poit and an .out-

let port and'having aconvex 'arcuatesurface comple- -mena-try to said concave arcuatesurface of said body and --in "sliding contacttherewith, said port block presenting a flat surface generally toward said driving head, a'first fluid operated piston operatively' engaging said .port'block *for applying a variable force to said-port block to slide said port block on said concave arcuate surface of said body to adjust the angle of said flat face with respect to the axis of rotation of said driving shaft and driving head, a cylin der block rotatably mounted on said port block positioned on said port block to be concentric with said driving head when said flat face of said portblock is normal to the axis of rotation of said driving head, said cylinder block having a flat face in contact with said flat face of said 'port block and covering the inlet and outlet ports in said port block, a universal coupling drivingly connecting said driving head and said c'ylinder block, a plurality of cylinder bores in said cylinder block spaced-angularly about said block and extending parallel to the axis of rotation thereof, said cylinder bores beingprovided with passages extending from each cylinder bore to the fiat face of said cylinder block that is in contact with the flat face of said port block, a piston in each said cylinderbore, ajpiston rod operatively connecting each saidpiston, to said driving head, said inlet and said outletport in'sai'd port block being each of arcuate shape'and positioned so that said passages extending from said cylinder bores register inturn with saidports as said cylinder block rotates, said inlet and outlet ports extendingfrom the fiat surface to the arcuate surfacein a direction'which isgenerally parallel to the axis of rotation'of thecylinder block, and a second fluid operable pistonsubjeoted to the fluid pressure pertaining in whichever of said ports is at the higher pressure, said second fluid operable piston acting on the port block to counteract forces tending to tilt the. port block out of contact with the arcuate surface.

'2. A pump or motor as claimed in claim 1 in whichsaid first and-second fluid operable pistons act on the'port blockat points adjacent the inlet and outlet'ports respectively. v 3. A pump or motor as claimed in. claim 2 in which the "fluid operable-piston which acts on the port block adjacent the port which is at' the higher pressure is subjected to thefluid pressure at that port whilst the other fluid operable piston is subjected to a control pressure derived from said, fluid pressure.

"4. A'ipump or motor as claimed in claim 3 in which said portblock has cylinders therein containing said fluid -operable'pistons, fluid connections communicating with said cylinders, and valve means for changing over the connections to said cylinders to ensure that said cylinders are always connected to the port-which is at the'higher pressure. I

References Cited by theExaminer UNITED STATES'PATENT-S i LAURENCE v. EFNER,Priinary Examiner. 

1. A HYDRAULIC DEVICE OF THE TYPE DESCRIBED, COMPRISING A MULTI-PART BODY HAVING AN INTERIOR SURFACE OF CONCAVE ARCUATE SHAPE, A DRIVING SHAFT ROTATABLY MOUNTED IN SAID BODY EXTENDING INTO SAID BODY OPPOSITE SAID CONCAVE ARCUATE SURFACE, A DRIVING HEAD FIXED TO SAID DRIVING SHAFT WITHIN SAID BODY OPPOSITE A PORTION OF SAID CONCAVE ARCUATE SURFACE, A PORT BLOCK INCLUDING AN INLET PORT AND AN OUTLET PORT AND HAVING A CONVEX ARCUATE SURFACE COMPLEMENTARY TO SAID CONCAVE ARCUATE SURFACE OF SAID BODY AND IN SLIDING CONTACT THEREWITH, SAID PORT BLOCK PRESENTING A FLAT SURFACE GENERALLY TOWARD SAID DRIVING HEAD, A FIRST FLID OPERATED PISTON OPERATIVELY ENGAGING SAID PORT BLOCK FOR APPLYING A VARIABLE FORCE TO SAID PORT BLOCK TO SLIDE SAID PORT BLOCK ON SAID CONCAVE ARCUATE SURFACE OF SAID BODY TO ADJUST THE ANGLE OF SAID FLAT FACE WITH RESPECT TO THE AXIS OF ROTATION OF SAID DRIVING SHAFT AND DRIVING HEAD, A CYLINDER BLOCK ROTATABLY MOUNTED ON SAID PORT BLOCK POSITIONED ON SAID PORT BLOCK TO BE CONCENTRIC WITH SAID DRIVING HEAD WHEN SAID FLAT FACE OF SAID PORT IS NORMAL TO THE AXIS OF ROTATION OF SAID DRIVING HEAD, SAID CYLINDER BLOCK HAVING A FLAT FACE IN CONTACT WITH SAID FLAT FACE OF SAID PORT BLOCK AND COVERING THE INLET AND OUTLET PORTS IN SAID PORT BLOCK, A UNIVERSAL COUPLING DRIVINGLY CONNECTING SAID DRIVING HEAD AND SAID CYLINDER BLOCK, A PLURALITY OF CYLINDER BORES IN SAID CYLINDER BLOCK SPACED ANGUARLY ABOUT SAID BLOCK AND EXTENDING PARALLEL TO THE AXIS OF ROTATION THEREOF, SAID CYLINDER BORES BEING PROVIDED WITH PASSAGES EXTENDING FROM EACH CYLINDER BORE TO THE FLAT FACE OF SAID CYLINDER BLOCK THAT IS IN CONTACT WITH THE FLAT FACE OF SAID PORT BLOCK, A PISTON IN EACH SAID CYLINDER BORE,A PISTON ROD OPERATIVELY CONNECTING EACH SAID PISTON TO SAID DRIVING HEAD, SAID INLET AND SAID OUTLET PORT IN SAID PORT BLOCK BEING EACH OF ARCUATE SHAPE AND POSITIONED SO THAT SAID PASSAGES EXTENDING FROM SAID CYLINDER BORES REGISTER IN TURN WITH SAID PORTS AS SAID CYLINDER BLOCK ROTATES, SAID INLET AND OUTLET PORTS EXTENDING FROM THE FLAT SURFACE TO THE ARCUATE SURFACE IN A DIRECTION WHICH IS GENERALLY PARALLEL TO THE AXIS OF ROTATION OF THE CYLINDER BLOCK, AND A SECOND FLUID OPERABVLE PISTON SUBJECTED TO THE FLUID PRESSURE PERTAINING IN WHICHEVER OF SAID PORTS IS AT THE HIGHER PRESSURE, SAID SECOND FLUID OPERABLE PISTON ACTING ON THE PORT BLOCK TO COUNTERACT FORCES TENDING TO TILT THE PORT BLOCK OUT OF CONTACT WITH THE ARCUATE SURFACE. 